Born to it

by Brendon Bosworth / 01.05.2009

It’s a brave new world. Not content with just screaming from the sideline and making sure little Jamie eats the right balance of protein and carbs to perform at his peak at the little league semi-final, super competitive parents, with nothing better to do but live vicariously through their children, can now ensure success by testing the genetics of their offspring to determine which sports they’ll be more capable at. Or can they?

The cotton wool swab won’t hurt young Jamie, as it glides along the inside of his mouth. But the results might. That’s if he’s old enough to comprehend the consequences. Cashing in on the latest fad in genetic testing, competitive parents are lining up their kids (some just out of nappies) to have their DNA analyzed for a particular gene, ACTN3, which is believed to influence how people perform in different sports. For a mere USD $149, Atlas Sport Genetics, the company that does the testing, will take their microscopes to Jamie’s DNA in order to predict if he’s better suited to power sports, like 100m sprinting and weightlifting, or if he should aim for a career as a marathon runner instead.

The science behind the tests is simple, if somewhat circumspect. We all have the ACTN3 gene floating about in the combination of 20,000 to 25, 000 genes that comprise the human genome. Everyone has two copies of this gene, one inherited from each parent. There are two variants of the gene. One, the R-variant, instructs the body to build a protein found exclusively in what are known as fast-twitch muscles. These are the muscles we use for rapid movements that require short, sharp burst of energy. They fire quickly and tire quickly too. The other variant, the X-variant, inhibits the production of fast-twitch muscle fibre.

The theory is: if you’re endowed with two copies of the R-variant, you’ll be packing a higher proportion of fast-twitch fibres and therefore better suited to power sports, like sprinting or 200m butterfly, that require quick bursts of speed. However, if you’re housing two of the X-variants, then you’ll have a higher proportion of slow-twitch muscle fibres. This doesn’t mean you’re a sluggish freak condemned to a life in slow-motion. Slow-twitch muscles are more efficient in using oxygen to generate energy and, although they fire at a slower pace, are great for endurance sports, because they can go for longer without getting tired. They’ll stand you in good stead for The Argus or the Two Oceans, that’s for sure. If you happen to have one copy of each variant (a very common occurrence) – well, that means you’ll probably do best at sports that mix it up a little. Pursuits that require endurance and power in equal measure: soccer, rugby, hockey, camel racing, that sort of thing.

A study published in 2003, by researchers in Australia, assessed 429 Aussie athletes, including 50 Olympians. The scientists discovered that half of the 107 sprint athletes had two copies of the R-variant, whilst all the male power sport Olympians had at least one copy of it. No female sprinter in the sample had two copies of the X-variant. On the other hand, roughly a quarter of the elite endurance athletes housed two copies of the X-variant.

Here in SA, however, a team of researchers, including sports science doyen Tim Noakes, found no significant correlation between 457 male Ironman tri-athletes and the XX-variant. And, according to a report in the New York Times, tests on a springy Olympic long-jumper from Spain proved he had vok all copies of the R-variant.

This begs the question: can we afford to turn these genetic variants into ‘god particles,’ the ultimate say as to what type of athlete our laaities should be? Not really. Sporting prowess, like any other skill, is contingent upon many interwoven elements: opportunity, training, mindset, nutrition. There could be homeless kids strutting around with two R-variants swimming inside their DNA, but they’ll never get the chance to prove themselves on the track. The closet they’ll ever get to world champ sprinting is running from the pigs or escaping the greasy clutches of a touring Austrian sex pest.

Furthermore, most of the research has focused on the distinction between power and endurance sports. There are numerous sports that involve a lot more than putting your head down and running for 20km. Hand-eye co-ordination, balance, timing, they all come into play. Current research suggests that athletic performance is affected by at least 200 genes.

“[At this stage] only a handful of genes have been identified as believed to be associated with certain types of sporting performance,” explains Prof. Malcolm Collins, Associate Professor and Senior Specialist Scientist at the MRC/UCT Research Unit for Exercise Science and Sports Medicine. “We have only started scraping the surface. We actually have no idea [just] how many genes are involved in athletic ability…[and] suspect there are different combinations for different sporting types, but there is a lot more work to be done.”

In an article on scienceblogs.com, Daniel MacArthur, one of the authors of the Australian 2003 study, breaks it down in simple terms:
“Super-elite athletes need to have the right ACTN3 combination, but they also have to have a whole host of other factors working in their favour – this one gene is just a minor ingredient in a large and complex recipe.”
“In fact, most studies performed so far suggest that ACTN3 explains just 2-3% of the variation in muscle function in the general population. The rest of the variation is determined by a wide range of genetic and environmental factors, most of which (particularly the genetic factors) are very poorly understood.”
Just to nail it home to moms and dads who are already building a glory room for all Jamie’s high-school medals, he adds: “There is no ACTN3 combination that is unique to super-athletes; instead, whatever combination your child has, he or she will share that with a large chunk of the population, the vast majority of whom will never go on to be international-level athletes.”

So, should Jamie go for his test or not? At age three, Jamie’s probably more interested in picking snails off the floor and stuffing them into his mouth than having his DNA probed. So let the boy be. If by age ten he’s pinning posters of Usain Bolt on his wall and spending all afternoon with a stopwatch out on the front lawn, well no-one should stop him from dreaming about that 100m dash, even if his genes are pointing towards a career as a hockey goalie instead. Hell, no-one has the right to interfere with his ambitions even if he’s got no legs. Just look at Oscar Pistorius, the blade runner, and all he’s achieved.

There’s no doubt that knowing your kid is potentially predisposed to doing better in a particular sport may help guide you in helping him or her with future athletic decisions. That’s if sport is really that important in your broader value system. But at the age of eight, does Jamie actually give a damn?

Great article. Very interesting. I just read a paper on 10 year olds trying out for sports teams, like Little League. They’ve found that the vast majority of professional athletes were born in the first few months of the year, because at 10 years old, an 11 month gap can make a huge difference in the child’s strength, maturity and ability. It’s quite scary how these aspects can totally dash a child’s dream.